Image:Vladimir Putin tried to harm Hillary Clinton's chances of being elected, said the report

Mr Putin most likely wanted to discredit Mrs Clinton because he blames her for inciting protests against his regime in late 2011 and early 2012, and because he resents her for disparaging comments she has made about him, the report said.

The report said Russian intelligence accessed "elements" of multiple state and local electoral boards, but "the systems targeted or compromised were not involved in counting votes".

US intelligence agencies also believe Moscow hacked into the emails of the Democratic National Committee and Mrs Clinton's campaign team and fed the material to WikiLeaks.

But the report claimed there were also targets associated with the Republican party.

Before he met spy chiefs for a briefing on the report on Friday, the President-elect dismissed the controversy as a "political witch-hunt".

He said he would appoint a team to "aggressively combat and stop cyber attacks" by coming up with a plan within 90 days of him taking office on 20 January.

Image:President Obama sent 35 Russian diplomats back to Moscow over the controversy

The President-elect said any hacking during the election campaign had no effect on the result and voting machines were not tampered with.

He said of the intelligence officials: "I have tremendous respect for the work and service done by the men and women of this community to our great nation."

He went on: "While Russia, China, other countries, outside groups and people are consistently trying to break through the cyber infrastructure of our governmental institutions, businesses and organisations including the Democrat National Committee, there was absolutely no effect on the outcome of the election."

He also claimed there were unsuccessful attempts to hack into the Republican National Committee.

Russia has denied the US government's hacking claims.

President Barack Obama last week imposed fresh sanctions on Moscow and expelled dozens of diplomats in retaliation.